Pneumatic operating assembly for air-blast circuit interrupters



PNEUMATI'C OPERAT AIR-BLAST CIRCUIT INTERRUPTERS Filed Jan. 29, 1949 B P. BAKER ET AL Fig.l.

IlM II I'NG ASSEMBLY FOR 2 Sheets-Sheet 1 INVENTORS Benjamin P. Baker 8 lloword M.Wilcox.

ATTORNEY July 21,1953 8. P. BAKER EI'AL PNEUMATIC OPERATING ASSEMBLY FOR AIR-BLAST CIRCUIT INTERRUPTERS 2 Shet's-Sheet 2 Filed Jan. 29, 1949 ohm - INVENTORS Benjamin P. Baker and AWL WITNESSES:

Howard M. Wii'cax.

ATTORN EY Patented July 21, 1953 UNITED srA es raiser FF-ICE PNEUMATIC O?ERATING ASSEMBLY FOR AIR-BLAST CIRCUIT INTERRUPTERS Benjamin P. Baker, Turtle Creek, and Howard M.

Wilcox, Pittsburgh, Pa, assignors to Westinghouse Electric Corporation, East Pittsburgh, Pa, a corporation of ?ennsylvania Application January 29, 1949, Serial No. 73,516

circuit-breakers have given an excellent account of themselves, both in this country and abroad, by reason of considerations of their safety, continuity of service, and reduced maintenance. These breakers, in the past, have been very greatly handicapped, however, by reason of their relatively high cost, and a considerable complexity of construction, and these difliculties became considerably magnified when attempts were made, even on paper, to design such breakers for more than 34.5 kilovolts, or for an interrupting capacity of more than 2.5 million kilovoltamperes.

We propose to provide a compressed-air breaker-assembly which has been completely redesigned and simplified, so as to be at the same time much less expensive to build, more rugged and reliable in operation, because of the fewer parts and the rearrangement of parts, and at the same time adapted for high-voltage service, such as 69 kilovolts or higher, and a high circuit-interrupting capacity, such as 3.5 million kilovolt-amperes.

The principal object of our present invention, as covered herein, is to provide an improved pneumatic operating-assembly for the abovementioned general combination, including an operating-mechanism which imparts something like a simple harmonic motion to the isolatingswitch (so as to avoid banging at the ends of travel), and which provides positive locks for holding the isolating-switch in either position at either extreme limit of its travel; and also to provide a pneumatic controlling and power-supplying means, for this mechanism, which provides the proper timing, and which, in the case of a gang-operated multipole breaker-assembly,

provides pneumatic interlocks for making sure that the air-blast interrupter-assemblies of all of the poles have completed their circuit-interruptin functions before the operating-mechanism is energized; and to provide other related 4:

pole assembly, and Fig. 2 is a similar view, viewed from a plane at right angles to that on which Fig. 1 was taken, but with certain parts thrown out of their proper planes or positions for the sake of diagrammatic representation, showing a three-pole breaker-assembly. embodying our invention, including certain diagrammatically indicated structural details and interlocks in connection with our operating-mechanism.

Figure 1 shows a single pole of a compressedair breaker-assembly embodying our invention. It is to be understood, however, that our invention is often or usually applied to a three-phase power-system, in which case each pole would consist of the structure as shown in Fig. 1, except that a single operating-mechanism may be used for gang-operation of all three poles, and possibly also a single compressed-air tank might be used for supporting the blast-tubes of all three poles.

Each pole of the breaker preferably has its own compressed-air tank or reservoir l, which is made of steel, and which serves also as a supporting-structure for the rest of the assembly. We provide a vertically disposed, insulating, blast-tube 2 which extends upwardly above the top of the tank and is supported by the tank. Inside of the tank, there is a vertically disposed tube-means 3, which is in alignment, and air-- flow communication, with the bottom of the blast-tube 2, so that said internal tube-means 3 serves, in effect, as a blast-tube extension which extends downwardly, within the tank, to a point near, but spaced from, the bottom of the tank, as indicated at Physically, this blast-tube extension, inside of the tank, could be a part of the insulating blast-tube 2, which could be made long enough to extend down to the point t near the bottom of the tank, but actually, it is more convenient to make the internal tube-means 3 out of iron or steel which is welded or otherwise properly secured within the tank l. Also, in a practical construction, it would be possible for the internal tube-means 3 to comprise the top part of an internal tube which physically extends from the top of the tank all the way down to the bottom of the tank, but which is provided with side-openings at the effective tubebottom 5, so that said tube-means would be intact, as a tube, only above the point l.

Disposed within the tank l, under the bottom d of the tube-means 3, is a blast-valved, which is accessible and operable from the bottom of the tank. The blast-valve 5 is preferably a differential-pressure valve, having a vertically movable inverted-cup member 5, which is pressed up, by a compression-spring i, into tight seating-engagement with the bottom end i of the tubemeans 3. The compression-spring 2 acts as a weal; closing-spring, which does not exert enough pressure to close the valve against the air-pressure in the tank 1, which may be at something of the order of 250 pounds per square inch. Normally, the blast-valve 5 is held closed by being supplied, from underneath, with air at the same pressure as the air in the tank l, as by means of a valve-controlling pipe 8, which is in communication with the underside of the movable inverted cup 6, so that the valve is thus held closed. [he valve is opened by releasing the air-pressure which is applied by the valve-controlling pipe 3, thus permitting the air-pressure i hin the tank to push down the inverted cup 5, thus permitting air to rush, in large quantities, upwardly through the internal tube-means 3 and through the insulating blast-tube 2.

On top of the insulating blast-tube we mount a single-column interrupter-asser y l9, which is preferably supported in a vertical position, in alignment with the blast-tube 2, and which is physically supported solely, or substantially entirely, by the blast-tube, so to be electrically insulated from ground by said blast-tube. This single-column interrupter-assernbly coin rises a plurality of vertically aligned, self-opening, longitudinal-blast interrupter-gap devices ii and. 52, two such gap-devices :eing used on a GQ-lailovolt breaker as illustrated. These gap-devices ii and ii are electrically connected in series, so that the current-fiow, in the normal closed position of the breaker, is from the top i of the interrupterassembly 553 to the bottom is thereof, a suitable line-terminal if; being provided at the top !3. Each interrupter-gap device ii and comprises a stationary contact-member MS or 12S, as the case may be, and a vertically movable contactmember HM or 52M, as the case may be. The two movable contact-members 55M and IZM are normally .oiased towards closed position by means of biasing-springs ii B and F3 respectively.

In the construction which is very much preferred, the first stationary contact-membe l is at the bottom i l of the interrupter-assembly ill, and is integrally or electrically united with a lower exhaust-chamber it, which is made of metal. The stationary contact-member Us is hollow, and extends down into the lower exhaustchamber 6, as show at $5.

In the preferred construction, the two movable contact-members HM and EM ar mounted within a metallic moving-contact assembly or housing which is the form of two concentric cylinders, namely as inner cylinder lit and an outer cylinder lie, so as to provide an annula' space lie between these cylinders, through which the air-blast may pass.

The moving-contact housing ll is vertically spaced from the lower exhaustchamber 18 by means of an insulating tube l6, which supports the outer cylinder Ho, and which is larger than the lower stationary contac -mernber HS, so as to provide an annular space 183 therearound, through which the air-blast may pass. In order to guide the air-blast from the blast-tube 2 into the annular space His, the lower exhaust-chamber i6 is provided with a funnel-like air-guiding duct l9, which is spaced from the lower end ill of the lower stationary contact-member HS, so as to provide an annular space its through which 4 the air-blast may pass, in moving upwardly from the blast-tube 2 into the annular space l8s.

The upper stationary contact-member 52S is integrally or electrically united with an upper exhaust-chamber 2%, which is similar to the lower exhaust-chamber IE, except that it lacks the funnel or duct 9 for carrying the blast-air upwardly on through the upper exhaustmhamber 2G. The upper stationary contact-member l2S is likewise of hollow construction, and its upper end is in communication with the space within the upper exhaust-chamber 2a This upper exhaustchamber 26 is supported on the top end of an insulating tube 2!, which is similar to the tube l8, except that the lower end of the top insulating tube 2! rests on top of the outer cylinder i'io of the moving-contact housing l'l. This upper insulating tube 2! is also larger than the upper stationary contact-member {23, so as to provide an annular space 2 Is which forms a closed upper end for the blast-air, as this blast initially moves upwardly through the interrupter-assembly IE3.

In the construction which is very much preferred, as illustrated, the upper end of the lower static-nary contact-member HS, and the lower end of the upper stationary contact-member 28 a e each provided with a centrally disposed orie 22, which is normally closed by the cooperating movable contact-member HM or 12M, as the case may be. The configuration of these movable contact-members HM and lZlVl is such ti o the pressure of the blast-air operates on e movable contact-members HM and l2M to to press them back away from their respective stationary contact-members i is and IE8, thus making the gap-devices ii and I2 self-opening, that is, making them open automatically, by them selves, as soon as a sufficient gas-pressure is built up in the spaces around them, without requiring any other device, not a part of the movingeontact assembly 5?, for causing a separatingmovement of the movable contact-members HM or 52M. opening-movement of the movable contact-members HM and iEM draws arcs between said members and thei associated stationary contact-membe's HS and liiS, respectively, thus initiating a circuit-interruptlng operation oi the breaker.

As soon as each movable contact-member 1 IM or 2M moves away from its normal contact making engagement with the end of its associated stationary contact-member MS or lZS, as the case may be, it uncovers the orifice 22 in the hollow stationary contact-member Us or 12S, thus permitting a blast of air to move longitudinally, or in a vertical direction, through the orifice 22 and thence through the hollow stationary contact-member Us or HIS, and thus acting powerfully to extinguish the are between the movable and stationary contact-members. The upper end of the hollow upper stationary contactmember 5253 dumps its air directly into the upper exhaust-chamber- 20, and the lower end of the lower hollow stationary contact-member 1 IS exhausts its blast of air into the lower exhaustchamber i5 by means of a plurality of tubular openings 23, which pass through the lower end l6 of the hollow lower stationary contact-mem ber HS, and also through the funnel or duct H) in the lower exhaust-chamber 16.

These upper and lower exhaust-chambers 2G and i6 thus provide an expansion-space in which the longitudinally moving air-blasts within the two stationary contact-members i IS and [28 may tacts begin to separate, and then a time sornething like cycle for the maximum contactseparation to be achieved. Then the arc may hang on for an additional time which may be slightly longer than the longest current-iiow period or half-cycle which could be expected under asymmetric-wave conditons.

It is desirable for the arc to be interrupted at the first important current-Zero (or sometimes possibly the second one), after full contact-separation has been achieved, disregarding (as unimportant from an arc-interrupting standpoint), any current-zero which may occur verysoon after full contact separation is obtained. Then it is desirable to prevent a restriking of the are on the next half cycle, and to this end it is necessary to have a large quantity of air-movement, a high air velocity, high turbulence, and cooling, or a combination of these factors. And then, in subsequent half-cycles, it is desirable to continue to have a sufficient dielectric strength of the air in the arcing-gap, so as to prevent any subsequent arc-restriking, and for this purpose, the air-pressure of the once-deionized and cooled gap-air is of service in providing dielectric strength to prevent a later breakdown of the gap.

Gur upper and lower exhaust-chambers 2t and It provide the gas-pressure in the gap-space. The. initial blast must be maintained until at least the first (or second) important current-zero after full gap-separation has been reached, but when cycles after the opening of the blast-valve 5. However, it is important that these exhaustchambers I6 and 126 should be present, and that they should develop an important back-pressure after said period of 2 cycles or the like, and it is important that these exhaust-chambers should be able to hold their back-pressure for a few cycles, or until a serially connected isolatingswitch 25 can be opened, as will subsequently be described. During this time, when a substantial back-pressure is being held in the exhaust-chambers i8 and 2c, the blast-valve must be kept open, as will readily be understood.

The air which accumulates in the two exhaustchambers iii and 2%) is cooled, in these cl'lambcrs, and is slowly dissipated to the atmosphere, through suitable exhaust-openings 2 5, which are provided in each of the exhaust-chambers I6 and 2t, and which may be provided with any desirable mufiling or sound-deadening or flame-extinguishing means (not shown), as is well understood in the compressed-air circuit-breaker art.

Since the movable contact-members HM and HM are opened by the air-pressure which is exerted by a large body of fast-moving air, in a blast which moves at a velocity approximating the velocity of sound, it is impractical to sustain such a large movement or blast of air for any considerable length of time. It is necessary, therefore, to

close the blast-valve 5 very quickly after it is opened, so as to conserve the high-pressure air or gas which is stored in the tank or reservoir 5. Consequently, after a circuit-interrupting operation by the isolating-switch 26, the blast-valve 5 is reclosed, and therefore the two movable contact-members I IM and IZM close again into contact with their respective stationary contactmembers HS and [25, so that these contactmembers thereafter remain closed throughout the time when the circuit should remain interrupted. It is necessary, therefore, as in the case of previously known self-opening, longitudinal-blast orifice-type circuit-breakers, to provide the previously mentioned isolating-switch 28 which is electrically connected in series with the interrupter-assembly ii).

We also provide a second vertically disposed insulating column 27, which is spaced from the blast-tube 2, and which also extends upwardly above the top of the tank i, so that it is supported by the tank, although it is not in pneumatic communication with the air within the tank I. This second insulating column 2'! is surmounted by a metal terminal-member 2B,

which is provided with a line-terminal 29, so as to provide the second line-terminal of the breakereassembly, the first line-terminal being the terminal 5 at the top of the interrupter-assembly iii. The isolating-switch '26 is movable so as to close or open an electrical circuit between this metal terminal-member 28 at the top of the second insulating column 21, and the bottom M or Id of the interrupter-assembly l5] which is mounted at the top of the insulating blast-tube 2. in the illustrated construction, the isolating switch 26 is pivotally connected to the lower exhaust-charnber 16, as indicated at 30, and its free end is movable into and out of contact with suitable contact-fingers 3i carried. by the metal terminal-member 28.

It is also a feature of our invention that an operating-mechanism is provided, as diagrammatically indicated at 33, in a location which is on, or close to, the tank I, and which is at substantially the same electrical potential as the tank, which would normallybe grounded. Thus, this operating-mechanism 33 is physically and electrically at the ground-level, which is of considerable advantage from the standpoint of the amount and size of the equipment which must be insulatedly supported, up in the air, as by the two insulating supporting-columns 2 and 21. The operating-mechanism 33 is operatively joined to the switch 25 through an insulating switch-operating rod 3d, for opening and closing the isolating-switch 26.

In accordance with some of the broader aspects of our present invention, the operatingmechanism 33 may be controlled in any desired manner which will permit or cause it to open the isolating-switch 2t, and lock it open, at the completion of the arc-interruption during the 'cpening operation of the interrupter-assembly it, and before the two movable contact-members HM and HM are spring-closed again after a reclosure of the blast-valve 5.

Some of the more specific aspects, or preferred structures, of our present invention are shown in Fig. 2, wherein a three-pole circuit breaker assembly is indicated. The three poles are, or may be, identical, except for the provision of a common operating-mechanism 33 which operates the isolating-switches 26 of all three poles, and a common electrically operated pneumatic trip-valve 38 which simultaneously opens all of the blast-valves 5, as will be subsequently described more in detail.

Confining our att ntion, for the moment, to the operating-mechanism 33, it will be seen, from Fig. 2, that this mechanism is associated with a crankshaft 3?, which turns through a limited motion of approximately 180, and vhich similarly operates a number of other crankshafts, such as 37A, 37B and BK, through suitable mechanical connecting-means, which have been diagrammatically indicated in the form of linkages or connecting-rods 38. The three auxiliary crankshafts 37A, 31B and 31C are associated with the respective poles of the breaker, and are provided with crank-members 39 which are connected to the respective insulating switchoperating rods 3 of the several poles, this connection being made in such manner that, at each of the extreme limits of motion of each crankshaft, the associated insulated switch-operating rod 3 1 is in complete toggle, so that the isolating-switches 28 are locked in both their open position and their closed position.

The principal crankshaft 3? of the operatingniechanisin 5,3 is illustrated as being provided with two auxiliary attachments, in the form of a compression-spring linkage it, which is crankconnected to the crankshaft .z'i, as indicated at in such manner that the compression-spring of this linkage presses the crankshaft toward either one of its limits of travel, once it has passed its central or 90 point in its travel from one extrezne limit of motion to the other extreme limit of motion. This compression-spring linkage #353 thus serves to hold the crankshaft 3'! in its extreme limit of motion, at either end of its direction of movement, so as to hold the crankshaft Si in such position that the toggleloc': is provided for holding the isolating-switches in either one of their open or closed positions, as the case may be.

The second auxiliary attachment which is associated with the main crankshaft 3'! of the operating-mechanism 33 is a shock-absorber, which is diagrammatically indicated at 4!, and

which is crank-connected to the crank-shaft indicated i, in such manner as to strong- 12.36 half of the rotating-movement ft 31, during either dir ction of i e crankshaft. When the crankegins to move, from either extreme I. s motion, the shock-absorber M is at ue ded or lengthened, and it oiiers practically no opposition to such movement. After the cranks ait passes its mid-point or 90 point, begins to contract the shock-absorber M, or to push together its telescoping cylinders, and this contraction is very slow and gradual at first, but becomes extremely rapid as the crankshaft 33' approaches the extreme limit or" its motion. The shock-absorber ii opposes this contraction, with a force which increases very rapidly as the velocity of compression is increased.

The general effect of this shock-absorber is to slow down the speed of rotation of the crankshaft particularly as it approaches the end of its motion, and as a result of this slow-down action, the crankshaft has a more nearly unim speed of rotation or movement, as disti guished from being constantly accelerated under the influence of the operating-force which is applied to it from the operating-mechanism 33, as will be subsequently described. In fact, the reaction of the shock-absorber actually decreases the angular velocity of the crankshaft at or near the ends of its travel.

As a result of the controlled speed of rotation of the crankshafts 31, 37A, 31B and 31C, the insulating switch-operating rods 34 impart a sort of sinusoidal type of motion to the several isolating-switches 26, so that these switches begin to move very slowly, but with a strong breakaway force, if necessary to overcome any 0pposition to the beginning of the switch-movement, and then the switches 28 move very rapidly near the mid-points of their swinging-movement, and finally they approach the end of their swinging-movement with a speed which gradually reduces to zero, so that there is no shock or banging of the isolating-switches 26 when they reach the limit of their travel, in either direction of movement, and at the same time the switches are capable of exerting a rather considerable pressure, for overcoming any obstacle or impediment near the extreme end of their swinging-movement, in either direction of operation.

The principal crankshaft 3? is rotated by means of a pinion 4?, which is engaged by a rack i2 which is connected to the operatingpiston or" the pneumatic operating-mechanism In addition to this operating-piston 44, the operating-mechanism 33 includes also a doublepiston air-valve 45, disposed with its two pistons 350 and the opposing each other. The left-hand air-valve piston 50, which controls the opening of the isolating-switches 26, is preferably larger than the right-hand piston 450, which controls the closing of the isolatingswitches Each of the air-valve pistons 450 and 50 is provided with its own air-inlet means 350 and i -3c, respectively, for applying air, under pressure, to the respective air-valve pistons.

The air-valve is provided with ports 41, 8, 49 and 53, which are so arranged that, when the switch-opening piston 150, is subjected to air-pressure from its inlet-means 460, it moves to the right, thus closing the port i! which dumps the air from the left-hand side of the operatingpiston id, and at the same time it opens the port d8 which leads the inlet-air into this lefthand side of the operating-piston 54, thus driving said operating-piston to the right, in a switch-opening movement. At the same time, the movement of the left-hand air-valve piston o pushes the right-hand piston 450 over to the right, thus causing it to open its dump-port 69 and close its port 5-9 which, when open, connects the space to the right of the operatingpiston dd with the closing-piston air-inlet means 480. It will be understood that the air-pressure and dumping-ports as and i? are both connected to the space to the left of the operating-piston 44, while the air-pressure and dumping-ports 5H and :8 are both connected to the space to the right of the operating-piston 44, the two dumping-ports 4'1" and 59 being for the purpose of exhausting air to the atmosphere, while the respective air-pressure ports 48 and 50 are for the purpose of supplying air-pressure to the operating-piston 5 3 from one or the other of the air-inlet means Q and 660, as the case may be. By this means, we provide what is known as functional dumping, for dumping the air which would otherwise be trapped behind the 0perating-piston 4:; when said piston is being moved in either direction of its travel.

In accordance with our invention, we also provide novel means for both timing the operating-.

mechanism 33 and providing a switch-opening operating-force therefor, in the form of compressed air which is supplied to the air-inlet means 460 of the switch-opening air-valve piston 450, and also, atthe same time (whenever the breaker-assembly has more than one pole), providing a pneumatic interlocking-means for making sure that the interrupter-assemblies ill of each or" the poles has completed its circuitinterrupting operation before the common operating-mechanism 33 is energized in the switchopening direction. In the more general aspects of our invention, we contemplate the use of any suitable means for performing these broadlystated functions. We have also provided speci'ficnovel means which may be advantageously utilized for the purposes stated.

Thus, as shown in Fig. 2, we, provide, near the top of each air-storage tank 6, and the bottom of each insulating blast-tube 2, of each pole of the breaker-assembly, a small bleedertube 55A, MB and MC, as the case may be. The central bleeder-tube MB is connected to the air-inlet means llio of the switch-opening air-valve piston 450 by means of two interlocking-valves 52A and 520, while the other two bleeder-tubes EIA and EIC are connected so as to supply air-pressure to operate the pistons 53A and 53C of the respective interlocking-valves 552A and 520. When no air-pressure is being supplied to these interlocking valves 52A and 52C, said valves are held in their non-o erated positions by means of springs 54. When these interlocking-valves 52A and 52C are operated, the movement or" their pistons uncovers ports which open a normally closed connection between the central bleeder-tube MB and the mechanisin-opening air-inlet means lso.

The several bleeder-tubes EIA, MB and BIG normally have no air-pressure therein, because the several blast-valves 5 are normally closed, and the compressed air which had last actuated the several interrupter-assemblies it has all leaked out. When the blast-valves 5 are first opened, to initiate a circuit-interrupter operation, large blasts of air travel upwardly, at sub stantially the velocity of sound, in the several insulating blast-tubes 2, and because of the high velocity of this air, the bleeder-tubes receive no effective or adequate air-pressure. first in-rush of the air-blast has been halted, at the top of the interrupter-assembly iii, the airpressure begins to build up, starting at the top, and travelling back downwardly, in a reflectedwave effect, still at a velocity approximating the velocity of sound, so that, at last, the several bleeder-tubes MA, MB and 5E0 all receive an effective or adequate air-pressure, which is greater than a predetermined minimum pressure to which the apparatus is effectually responsive.

The time required for this air-wave to travel up, and to be reflected down again, is really very small, but so is the time required to eiiect a circuit-interrupting operation of the several interrupter-assemblies iii. In addition to the time required for a pressure-wave to appear at the inlets of the several bleeder-tubes MA, 51B and F40, there is to be added also the time necessary for the interlocking-valves 52A and 52C to open, the time necessary for the air valve 5:5 to move from its left-hand position to its righthand position, and the time necessary for the operating-piston M to move to the right, against the inertia of the operating-mechanism itself and of the several isolating-switches 2%, together When the r Iii with the mechanical interlinkage between the mechanism and the switches. All of this time adds up to a switch-operating time-delay in getting the several isolating-switches 26 separated from their several contact-fingers 3i, and this switch-operating time-delay is timed to be slightly longer than the three cycles (more or less) which are required for completing a circult-interrupting operation in all of the interrupter-assemblies it, under the most adverse opcrating-conditions.

The operating-mechanism 33 is closed by means of an electrically energized closing-valve l ch is illustrated as having an operatingcoil 22" which, wh n electrically energized, opens the Closing-valve, and admits compressed air from oneor all of the tanks or reservoirs l to the sw tch-closing air-inlet means 460 of the airvaive of the operating-mechanism 2 3. This causes the right-hand air-valve piston 450 to move to the left, pushing the left-hand piston 50 with it, thus admitting compressed air from the air-inlet means lec to the right-hand side of the operating-piston t l, while dumping air from the left-hand side of this piston. This causes the mechanism to close each of the isolatring-switches it, and to lock them in their closed positions, by reason of the previously-described toggle-action.

The smaller size of the switch-closing airvalve piston isc, as compared with the switchopening air-valve piston in our preferred form of construction, insures that whenever there is a conflict between the switch-opening means and the switch-closing means, that is, when air is being admitted to both pistons 450 and 50 at the same time, the force exerted by the switch-opening piston lto will prevail, and will cause a switch-opening operation.

In accordance with our invention, as previously intimated, we also provide a common electrically energized tripping-valve 35, which is connected, by means of piping 57, to all three of the blastalve pipes 8. In the normal, tie-energized posi- Eii, i

"tion or" the tripping-valve 36, as shown in Fig. 2,

compressed from one or all of the tanks I, in communication, through this valve, with the undersides of all three of the blast-valves 5, thusv holding these blast-valves in their normal closed positions. The tripping-valve 36 is provided with an operating-coil 58 which, when energized, opens a pilot-valve it which applies the compressed-air pressure to a main valveope-rating piston 58, which closes. the air-inlet side of the tripping-valve, at the point indicated at iii, and at the same time opens a dumpingport, at so as to dump the air from the piping El and 8, so as to remove the air-pressure from the undersides or the several blast-valves 5, causing all of these blast-valves to open simultaneous y, under the influence of the air-pressure within their respective tanks l.

it is impracticable to permit the several air-blasts to continuously travel through the several interrupter-assemblies ill for any material length of time, after the three cycles, more or less, which are necessary for completing the circuitdnterrupting operation, it is quite desirable to automatically reclose the several blast-valves 5. To this end, we have diagrammatically indicated the operating-mechanism 3;- as being provided with an interlock-switch 53, which is diagrammatically indicated, for the sake of making a simple schematic indication, as being disposed at the right-hand end of the rack 43, so

that, when the rack moves in a switch-opening direction, it opens the interlock-switch 63, and thus interrupts the energizing-circuit 64 which is connected to the operating-coil 58 of the tripping-valve 36.

In this manner, the tripping-valve 36 is automatically ale-energized, so that it again applies the same air-pressure, underneath each of the blast-valves 5, as the air-pressure within the several tanks i, so that the differential pneumatic operation of these blast-valves, aided by the several closing-springs 1 of said valves results in the restoration of the said blast-valves to their normal closed. position. This stops the supply of an air-blast to each of the interrupterassemblies I8, and the air which is already entrapped in said assemblies soon leaks out, permitting the movable contact-members HM and l2M to return to their normal closed positions in contact with the respective stationary contactmembers HS and IZS, as the case may be. This reclosure of the interrupter-assembly contacts does not, however, ei fect a reclosure of the circuit-breaker assembly, because the several isolating-switches 26 are now locked in their open positions, in which position they will remain until there is an energization of the closing-valve 55.

Various details of the breaker-assembly, which is herein generically or broadly described and claimed, are described and claimed in more detail other copending applications. Certain structural details of the interrupter-assembly it, for mechanically holding the parts of this assembly together, are shown in more detail, and specifically claimed, in a copending application Serial No. 74,407, filed February 3, 1949, by Benjamin P. Baker, Erling Frisch, and Howard M. Wilcox, now U. S. Patent 2,602,868, issued July 8, 1952. Certain details and improvements in the interrupter-assembly [0, relating to the functional operation of this assembly, and a practical operating-form thereof, are disclosed and claimed in a copending application Serial No. 74,406, filed February 3, 1949, by Benjamin P. Baker, Erling Frisch, Wayne S. Aspey and John B. MacNeill, now U. S. Patent 2,627,005, issued January 27, 1953.

While we have described and illustrated our invention in but a single illustrative form, which is shown somewhat diagrammatically or ideally, we wish it to be understood that we are not limited to the precise form which is illustrated, as those skilled in the art could readily make various changes of substitution, omission or addition, without departing from the essential spirit of our invention. We desire, therefore, that the appended claims shall be accorded the broadest construction consistent with their language.

We claim as our invention:

1. A compressed-air circuit-breaker assembly comprising: a compressed-air tank; an air-blast interrupter-assembly; a blast-tube for at times supplying said interrupter-assembly with an airblast from said tank; said blast-tube extending away from a wall of the tank, the entrance-end of said blast-tube being hermetically connected with said wall of the tank and being open to the interior of said tank; a normally closed blastvalve within said tank, said blast-valve comprising a closure-member which is movable toward and away from the entrance-end of said blasttube, and means for providing a valve-chamber back of said closure-member for at times pressing said closure-member into its closed position; a

valve-controlling tripping-means operating, in its deenergized condition, to apply a valve-closing. air-pressure to said valve-chamber back of said closure-member, said tripping-means operating,- in its energized condition, to dump air-pressure from said valve-chamber, thereby causing said blast-valve to open; an isolating-switch; means for electrically connecting the isolating-switch in series-circuit relation to the air-blast interrupter-assembly; an operating-mechanism for said isolating-switch; means for energizing saidtri ping-means; means for operating the oper ating-mechanism so as to cause said isolatingswitch to open and to become locked in its open position when the interrupter-assembly has com-' pleted its circuit-interrupting operation; and means responsive to an opening movement of said operating-mechanism for deenergizing said trip-- ping-means.

2. A compressed-air circuit-brealter assembly comprising: a compressed-air tank; an air-blast interrupter-assembly; a blast-tube for at times supplying said interrupter-assembly with an airblast from said tank; a normally closed blastvalve for controlling the communication between said blast-tube and said tank; a valve-controlling tripping-means which, when energized, causes said blast-valve to open, and which, when deenergized, causes said blast-valve to close; an isolating-switch assembly including an isolatingswitch with an operating-mechanism therefor having a crankshaft which turns through a limited motion of approximately an insulating switch-operating rod connected between said isolating-switch and said crankshaft in such manner as to be in complete toggle with respect to said crankshaft at each limit 05 motion of i crankshaft, means for applying an operating force for turning said crankshaft in either direction, at will, from one limit of its motion to the other, shock-absorbing means for checking the crankshaft-movement as it approaches either limit of motion in either direction of movement, and biasing-spring-means for forcing said crankshaft toward its limit of motion in either the open or the closed position of said isolatingswitch so as to hold said crank-shaft in its toggle position for locking said isolatingwitch in its open or closed position as the case may be; means for electrically connecting the isolatingswitch in series-circuit relation to the air-blast interrupte=assembly; and means responsive to a predetermined amount of opening-movement of said isolating-switch mechanism for deenergizing said tripping-means.

3. A multipolar compressed-air circuit-breaker assembly comprising: a separate pole-assembly for each pole of the breaker, each pole assembly comprising: a comp 'essed-air source; an airblast interrupter-assembly; a blast-tube for at times supplying said interrupter-assembly with an air-blast from said compressechal' source; a normally closed blast-valve for controlling the communication between said blast-tube and said compressed-air source; an isolating-switch; and means for electrically connecting the isolatingswitch in series-circuit relation to the air-blast interrupter-assembly; said multipolar assembly further including: a valve-controlling trippingmeans which, when energized, causes all f said blast-valves to open, and which when deems"- gized, causes all of said blast-valves to close; and an isolating-switch operating-mechanism; characterized by said operating-mechanism comprising: a double-piston air-Valve, disposed with the two pistons opposing each other, one of said pistons being for a switch-opening operation, and the other for a switch-closing operation; airinlet means for applying air under pressure to each of the air-valve pistons, respectively; a mechanism-operating piston associated with said double-piston air-valve; the airvalve being so arranged that, when either of its pistons is actuated by its inlet-air, it admits said inlet-airto that end of the operating-mechanism piston, and also actuates the other air-valve piston to cause it to dump air from the other side of the operating-mechanism piston; switch-opening pipemeans for, at times, applying air-pressure to the switch-opening air-inlet means of said air-valve; and switch-closing pipe-means for, at times, applying air-pressure to the switch-closing air-inlet means; characterized by said switch-opening pipe-means including pneumatic interlockingmeans for responding to a predetermined airpressure in each of said blast-tubes, and for thereupon applying air-pressure to the switchopening pipe-means; and means responsive to an opening movement of said operating-mechanism for deenergizing said tripping-means.

4. A multipolar compressed-air circuit-breaker assembly comprising: a separate pole-assembly for each pole of the breaker, each pole-assembly comprising: a compressed-air source; an airblast interrupter-assembly; a blast tube for at times supplying said interrupter-assembly with an air-blast from said compressed-air source; a normally closed blast-valve for controlling the communication between said blast tube and said compressed-air source; said blast-valve comprising a closure member which is movable toward and away from the entrance-end of said blasttube, and means for providing a valve-chamber back of said closure-member for at times pressing said closure-member into its closed position; an isolating-switch; and means for electrically connecting the isolating-switch in series-circuit relation to the air-blast interrupter-assembly; said multipolar assembly further including: a valve-controlling tripping-means operating, in its deenergized position, to apply a valve-closing air pressure on all of the blast-valves of the breaker, said tripping-valve operating, in its energized position, to dump air-pressure from all of said blast-valves, thereby causing said blastvalves to open; and an isolating-switch operating-mechanism; characterized by said operatingmechanism comprising: a double-piston airvalve, disposed with the two pistons opposing each other, one of said pistons being for a switchopening operation, and the other for a switchclosing operation; air-inlet means for applying air under pressure to each of the air-valve pistons, respectively; a mechanism-operating piston associated with said double-piston air-valve; the air-valve being so arranged that, when either of its pistons is actuated by its inlet-air, it admits said inlet-air to that end of the operating-mechanism piston, and also actuates the other airvalve piston to cause it to dump air from the other side of the operating-mechanism piston;

switch-opening pipe-means for, at times, ap-

plying air-pressure to the switch-opening airinlet means of said air-valve;.and switch-closing pipe-means for, at times, applying air-pressure to the switch-closing air-inlet means; characterized by said switch-opening pipe-means including initiating means responsive'to the aforesaid blasting-operation; and means responsive to an opening movement of said operating-mechanism for deenergizing said tripping-means.

5. A multipolar compressed-air circuit-breaker assembly includin a separate pole-assembly for each pole of the breaker, each pole-assembly comprising: a compressed-air source; an airblast interrupter-assembly; an insulating blasttube for at times supplying said interrupter-assembly with an air-blast from said compressedair source; a normally closed blast-valve for controlling the communication between said blast-tube and said compressed-air source; a valve controlling tripping means which, when energized, causes said blast-valve to open, and which, when deenergized, causes said blast-valve to close; an isolating switch; means for electrically connecting the isolating switch in series circuit relation to the air-blast interrupter assembly; an operatin mechanism for said isolating switch; means for energizing saidtripping means, means for energizing said operating mechanism to open said isolating switch including a mechanism piston, a conduit leading compressed air from one of the blast-tubes on the downstream side of the blast-valve for said one blast-tube to the operating mechanism for the isolating switch to actuate said mechanism piston, an interlock valve in said conduit for at least one of the other blast tubes, and another conduit leading from said interlock valve to the other blast-tube on the down-stream side of the 'blast-valve therefor so that the isolating switches will not open unless there is blast pressure in each of the blast tubes thereby assuring opening of the interrupter assemblies prior to operation of the respective isolating switches.

BENJAMIN P. BAKER. HOWARD M. WILCOX.

References Cited in thefile of this patent UNITED STATES PATENTS 

